1. Field of the Invention
This invention relates to a hydraulically fixable flange as well as to a rotary knife used as upper and lower pair with the hydraulically fixable flange, which are used when disc-shaped rotary knives, grinding wheels, gears, cutters and a like are fitted on the shaft, or when the shaft is used in tools like end mills, drills, jigs, positioning devices and the like fixed to fitting holes.
2. Description of the Prior Art
Such art as shown in FIG. 1 is conventionally known as a hydraulically fixable flange of this kind, wherein a ring-shaped tool 104 is fixed to one end of the periphery of a flange body 100 with a bolt 102. An annular hydraulic chamber 106 is formed within the flange body 100, and a piston 112 with a movable O-ring 110 is mounted in a radial direction from a flange body 100 within the piston chamber 108 connected to this hydraulic chamber 106. A set screw 118 is fastened at the center of a hollow cover 116 which is fixed to the flange body 100 by a bolt 114.
In such conventional hydraulically fixable flanges the pressure of pressurized oil within the hydraulic chamber 106 is increased with the piston 112 pressed onto the side of the hydraulic chamber 106 by screwing the set screw 118. The bore of the flange body 100 is contracted to provide the prescribed tightening force required for clamping.
However, the space with the shaft is larger or the fixing force is higher in the conventional hydraulically fixable flange. Thus, the number of pistons 112 must be increased, because the amount of oil to be supplied to the hydraulic chamber 106 by the movement of the piston 112 becomes less when the pressure in the hydraulic chamber 106 is caused to increase, or when the width of the flange becomes wider. Consequently, there is insufficient rigidity and strength of the flange body 100' which requires higher accuracy and a larger number of parts leading to economic disadvantages. Another drawback is that the volume of oil enclosed within the flange body 100 may change during the summer and the winter due to expansion and contraction of oil caused by temperature variances, which weakens the clamping force and makes the fixing impossible, or it becomes hard to attach and detach because of the contraction of the bore in advance.